Coincidence indicator for electronic counters



Aug- 7, 1951' JX. P-EusLEY ETAL 2,563,106

COINCIIDENCE INDICATOR FOR ELECTRONIC COUNTERS Filed April 28, 1948 l//GH FREQUENCY Cdl/VC/DEA/CE hva/C470# Patented Aug. 7, 1951 oOiNOIDENcE INDICATOR FOR ELECTRONIC ooUN'rERs J enness P. Eugley, Runnemede, N. J and Robert R. Freas, Jr., .lei-myn, Pa., assignors to Radio Corporatipfn ci America, a corporation of Dela- Ware i Application Apr-i128, 194s, serial No. 23,816

2 Claims. 1

This invention relates to coincidence indicators for electronic counters including a pluralti7 of tandem connected` ltrigger circuits of the type wherein a pair of triodels (l) have operating potential applied to their anodes through a common resistor and thence through separate resistors, (2) have their ancdes` each. cross-.connected to the grid of the other through a resistor whichis Ashunted by a capacitor, (3) have their grids grounded through separate resistors, and` (4) have their cathedes connected to a lead maintained at a suitable negative potential.

As is well known, with such connections, current conduction is stable in one or the other anode of each trigger circuit and is transferred from `one anode 'to the other in response vto the application of. a negative pulse at thejunotion between the commonand separate anode resistors.

It is also well understood that in the operation lof lsuch a counter, input pulses are `applied to the common anode resistor terminal of the trigger circuit or counter stage which operates at the highest frequency and that each of the .succeedf zllg counteristages has its commonanode resistor .terminal vcoupled to that anode of .the imrnef diatel-y preceding stage' which conducts current when suchpreceding stage -is in a binary l0 condition. Thus for every two pulses fed to the rst :counter state, ,one square wave is'produced. at

the anodes of the first stage, for every four pulses lj fed to the first 4 counter stage, one square wave is produced at the anodesof .the second stage, etc.l

lt is well known that each group of four trigger vcircuits of the counter may be provided with feedback connections k(l) between the binary l anode of the third trigger circuit and the binary `0r grid of the second trigger circuit and (2) between the binary lanode of the fourth trigger circuit and the binary 0 grid of the third trigger circuit `so that each group of -four trigger circuits lcompletes its cycle of operation in response to the application of ten pulses to the commonane ode `resister terminal 4of the lowest orderor high- .est frequency trigger circuit. Such a group of trigger circuits, i's"her e inafter .called a decade aiidach trigger circuit of the Counter ,slhe'reinf 4fatter called a stage.

#The counter to which the 'nnp roved .coincidence indicator of the present invention lis ap.-

;Plied .includes three defedes and the Output .leali `ofthe 'highest order or lowest frequencydecade is coupled to the common anode resistor terminal of the -irst of'agroup'oi two trigger circuits which function like a binary counter.

lAs disclosed in a copendingapplic'ation of J-Bussfseriai No. ccd2-14 diedi1 March 21, 194:1',

now Patent No. 2,521,"2Y4 issued September 12, 1950 each of the. three decades and the binary counter have their anodes connected to the fixed contacts of a differentl count selector switch. The fixed contactsof these switches are so var ranged that any count from 0 to 9 of a decade or either the 0 or 1 count of the binary "counter may be selected by moving switch outputccn- Ytacts into engagement with the different fixed contacts. y

The coincidence indicator of the present invention has its input leads connected to the se: lector switch output contacts and functions to deliver one output pulse in'response' to the count selected by these switches. With the illustrated form of the invention, the count thus selected may be anything from 0 to 2000. If the input pulses have a frequency of 100 kc., it is apparent that the selector switches are operable to produce between the rst input pulse and the outputpulse a time delay which may. be varied in 10 -microsecond steps and may be anything from `0'to 29,000 microseconds.

The coincidence indicator of the present invention includes (l) a high frequency coincidence indicating circuit which has vits input leads connected to the output contacts of the selector switch of the rst decade and delivers one `output pulse Yin response to the selected count of the first decade, (2) a pair of pentodes which have their lirst and third grids connected to the output contacts of the selector switches of the` second and third decades and the binary counter and (3) an output combining circuit Vwinch functions to deliver van output pulse in response to the count selected `by the various switches. Thisco.- incidence indicator has the advantage that it requires a minimum of tubes and functions in re- Spanse if the .Selected count Qi the Second arid `third decades andthe binary counter to pro. Y` ,duce a single voltage pedestal kon which is superimposed the output voltage of the high rirequency coincidence indicator. This two level voltage is utilized to nre a gaseous conduction device or thyratron which has in its cathode lead a resistor from the high voltage terminal of which an Aoutput pulse of high amplitude is derived.v

rIfhre principal 4object of the invention is the Drei/Sian of an improved. coincidence' indicator and method of operation which involve aniini.- mum of parts. An additional object is to pro..- vide a coincidence indicator which avoids the production of control .yoltages having a different ylevelngor each o' the Idecades `and the binary muster.

The invention will be better understood from switch S2, a third decade 84 which has a count selector switch S3 and a two stag`e`section 85 which has a count selector switch S4.

Input pulses are applied to the `-irst stage'VIl 1 through a capacitor I0. Each ten input pulses cause one pulse to be applied through a capacitor' 82 to the input of the decade 83, each one hundred input pulses` causes one pulse to be applied through a capacitor 86 to the input of the decade 84 and each one thousand input pulses causes one pulse to be applied through a capacitor 91 to the input of the two stage section 85. Otherwise stated, the counting range of each of the decades is ten, the counting range of the two stage section is two and the counting range of the counter is two thousand; Any count of the units is selected by the switch SI, any count of the tens is-selected by the switch S2, any count of the hundreds is selected by the switch S3 and either count of one or two thousand is selected by the switch S4.

The detailed connections of the decade VI to V4 and its selector switch SI appear in Figure 2. The connections of the decades 83 and 84 are like that of the stage VI to V4 and have been shown in the form of boxes. The two stage section 85 'and its count selector switch S4 involve no un obvious connections and have been shown in the form of boxes.

It will be noted that the decade VI to V4 has operating potential applied from a -l-B lead I9 to its successive stages through common anode resistors to 23 and that the other connections of each of these stages `are as explained above. In the binary 0 condition of these stages, current conduction is in the anodes I2, I4, 6 and I8 as indicated by the arrows adjacent the separate or individual anode resistors. In the binary 1 condition of the stages, current conduction is in the anodes II, I3, I5 and I1.

The stages are connected in tandem through the medium of coupling capacitors 26, 2': and 28, the binary 1 anode I5 of the stage V3 is coupled to the binary 0 grid of the stage V2 through a capacitor 62 and a resistor 63, and the binary 1 anode I1 of the stage V4 is coupled to the binary 0 grid of the stage V3 through a capacitor 90 and aresistor 6|. `With the connections of the decade VI to V4 as indicated, the square wave form voltages appearing at the anodes to I8 are as indicated in Figure 1. In this lgure, the count of the decade Vi to V4 is indicated by the numerals 0 to 9 at the top of the figure and the particular anode voltages selected by the switch SI for the various counts are indicated by dots. Such selected counts are indicated by the numerals 0 to 9 appearing at the leftof the horizontal rows of xed contacts of the switch SI of Figure 2. For example, if a count of 4 is to be selected, the switch output contacts 29, 30 and 3| are moved to the 4 position and the voltages of the anodes Il, I6 and |1, which have the maximum voltage si- 4 multaneously only for the count of 4, are selected. The voltages of other anodes having their maximum voltage simultaneously only for the selected count are applied to the switch output contacts 29, 39 and 3| in a similar way.

Counter loading limitationsmake it desirable that the anode voltages be applied to the fixed contacts of the selector switches through isolating impedance elements such as the resistors 10 to 11 which are each shunted by a capacitor.

The anode voltages selected by the switch output contacts .29, 30 and 3| are coupled through capacitors 32, 33 and 34 to the input leads of a high frequency coincidence indicator 35. When the decade VI to V4 attains the count selected by the contacts 29,39 and 3|, there appears at the output lead 36 a voltage pulse of a form somewhat like that indicated at 31.

The selector switch S2 has output contacts 38, 39 and 48 which are connected through capacitors 4|, 42 and 43 to leads 44, 45 and 46. Similarly the selector switch S3 has output contacts 41, 48 and 49 which are connected through capacitors 50, 5| and 52 to leads 53, 54 and 55. The switch S4 has an output contact 56 which is connected through a capacitor 51 to a lead 58.

It will be noted that (1) the lead 44 is connected to the grid 59 of a multigrid tube such as pentode 60, (2) the leads 45, 46 and 53 are connected to the grid 6| of the pentode 60, (3) the lead 54 is connected to the grid 62 of another multigrid tube such as pentode 63 and (4) the leads 55 and 58 are connected to the grid 64 of the pentode 63.

From a 12.5 volt lead 65 bias potential is applied (l) through resistors 66 and 61 to the grid 59, (2) through resistors 60 and 69 to the grid 6 I, (3) through resistors 66 and 18 to the grid 62, and (4) through the resistors 68 and 19 to the grid 94. These various bias potentials are made such that the pentodes 60 and 63 conduct current only when all the switch output contacts to which their grids are connected have their maximum voltages. Thus the pentodes 60 and 63 simultaneously conduct current only in response to the count selected by the switches S2, S3 and S4.

Operating potential is applied from a 160 volt lead through a resistor 8| to the anode 88 of the pentode 66 and through a resistor 89 to the anode of the pentode 63.

A pair oi triodes 9| and 92 have their anodes 93 and 94 connected through a common resistor 95 to a 315V lead 96 and have their grids 91 and 98 connected to the lead 96 through the resistors 99 and |00. With these connections, the triodes 9| and 92 are normally conducting current through the resistor 95, the grids 91 and 98 are biased to zero, and the voltage drop of the resistor 95 is substantially constant. This voltage drop of the resistor 95 is maintained so long as the grids 91 and 98 are not biased to cutoff simultaneously.

' The grids 91 and 98 are connected through the capacitors I0| and |02 to the anodes 88 and 90 of the pentodes 60 and 63. When these pentodes conduct current simultaneously, both the grids 91 and 98 are biased to cutoff, the current through the resistor 95 is interrupted and a positive pulse is applied through a capacitor |03 and an isolating impedance element |04-I05 to the lead |06.

Since the lead |06 is connected to the lead 36 through a capacitor I 81, the high frequency pulse 31 is combined with the pulse applied from the resistor 95 toform a two level voltage pulse something like that indicated at 108. Obviously the pulse l08 attains its maximum amplitude only inY response to the count selected by the selector switches SI, S2, S3 and S4.

The pulse 108 is applied to the grid |09 of a thyratron ill] which has operating potential applied to its anode lll from a lead H2 through resistor H3, has its anode HI connected to ground through a bypass capacitor H4, has a resistor H5 in its cathode lead, and has its grid |09 so biased through a 50 volt lead H6 that it conducts current only when the pulse |08 has its maximum amplitude.

When the thyratron H0 conducts current a positive output pulse of high amplitude is produced at the lead H1. Obviously such output pulse may be applied to the binary 0 grids of the different counter stages for resetting the counter to its zero condition or may be otherwise utilized.

What the invention provides is a coincidence indicator which (l) includes a minimum of component parts, (2) involves the production of a control pulse having only two voltage leads, and (3) is operable to select any count between 0 and 2000. It is apparent that the illustrated form of the invention may be extended to include additional decades or counter sections which have the output contacts of their selector switches suitably connected to the grids of the pentodes 60 and 63.

We claim as our invention:

1. In a coincidence indicator for producing an output pulse in response to different counts of a counter wherein a plurality of stages are connected in tandem and are arranged in groups each having a selector switch to the output contacts of which maximum voltages are applied only in response to the selected count of that group and wherein the lowest order of said groups is followed by a plurality of higher order groups, the combination of a pair of multigrid electron discharge tubes having their grids connected to the output contacts of all of said selector switches except that of the lowest order of said groups so that said multigrid electron discharge tubes conduct current only in response to the maximum potentials of all the switch output contacts to which their grids are connected, means responsive only to simultaneous conduction of current y by both of said multigrid electron discharge tubes for producing a rst voltage pulse, means for producing a second voltage pulse only in response to the maximum voltages of the output contacts of the selector switch of the lowest order of said groups, and means for superimposing said second voltage pulse on said rst voltage pulse to form a two level control pulse.

2. In a coincidence indicator for producing an output pulse in response to different counts of a counter wherein a plurality of stages are connected in tandem and are arranged in groups each having a selector switch to the output contacts of which maximum voltages are applied only in response to the selected count of that group and wherein the lowest order of said groups is followed by a plurality of higher order groups, the combination of a pair of multigrid electron discharge tubes having their grids connected to the output contacts of all of said selector switches except that of the lowest order of said groups so that said multigrid electron discharge tubes conduct current only in response to the maximum potentials of all the switch output contacts to which their grids are connected, a resistor, means including a second pair of electron discharge tubes interconnected to conduct current through said resistor only when said multigrid electron discharge tubes are not conducting current simultaneously, and means for deriving a first voltage pulse from said resistor in response to interruption of the currents of said second pair of electron discharge tubes, means for producing a second voltage pulse only in response to the maximum voltages of the output contacts of the selector switch of the lowest order of said groups, and means for supermposing said second voltage pulse on said first voltage pulse to form a two level control pulse.

JENN'ESS P. EUGLEY. ROBERT R. FREAS, JR.

Electronic Industries for July 1945, pages 97, 98, 99, 130, 134, 138, 143 and 146.

Electronics for March 1947, pages 120, 121, 122 and 123.

Electronics for February 1948, pages 88-93.

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